81747513 has 6 divisors (see below), whose sum is σ = 118079754. Its totient is φ = 54498336.

The previous prime is 81747511. The next prime is 81747529. The reversal of 81747513 is 31574718.

It can be written as a sum of positive squares in only one way, i.e., 64208169 + 17539344 = 8013^2 + 4188^2 .

It is not a de Polignac number, because 81747513 - 2¹ = 81747511 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81747511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4541520 + ... + 4541537.

It is an arithmetic number, because the mean of its divisors is an integer number (19679959).

Almost surely, 2^81747513 is an apocalyptic number.

It is an amenable number.

81747513 is a deficient number, since it is larger than the sum of its proper divisors (36332241).

81747513 is a wasteful number, since it uses less digits than its factorization.

81747513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9083063 (or 9083060 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 81747513 is about 9041.4331275523. The cubic root of 81747513 is about 434.0017856185.

The spelling of 81747513 in words is "eighty-one million, seven hundred forty-seven thousand, five hundred thirteen".